As a next-generation high speed wireless communication scheme (or, a next-generation high speed wireless communication system), development of an LTE (Long Term Evolution) is currently advancing. The LTE has a wide bandwidth of 20 MHz at maximum, adopts OFDMA (Orthogonal Frequency Division Multiple Access) and MIMO (Multiple Input Multiple Output) for download traffic, and adopts SC-FDMA (Single-Carrier Frequency Division Multiple Access), etc., for upload traffic, so as to realize the download traffic of over 300 Mbps at maximum and the upload traffic of 75 Mbps at maximum.
Because the LTE is a communication scheme specialized in a packet communication, it is assumed that conventional communication schemes, such as W-CDMA and cdma2000 1x, are utilized for a voice communication through circuit switching even if a wireless communication terminal can utilize the LTE. In wireless communication terminals which always stand by for both wireless communication system for voice communication and LTE system, a current consumed in a normal standby mode of the wireless communication terminals is large. In wireless communication terminals which stand by only for the LTE system, an incoming call cannot be received in a normal mode, so that a function as a so-called “telephone” cannot be held. In wireless communication terminals which stand by for only the wireless communication system for voice communication, it is not possible to make use of an advantage which is the continuous IP connectivity of the LTE.
In order to overcome such problems, a function called a CS (Circuit Switched) Fallback has been thought out for the LTE system. According to the CS Fallback, an audio incoming-call notification from the wireless communication system for voice communication, such as W-CDMA or cdma2000 1x, is transmitted to a wireless communication terminal by tunneling over the LTE system. The wireless communication terminal which received the audio incoming-call notification performs a temporal withdrawal (Suspend) process on the LTE system, performs a connection establishing process on the wireless communication system for voice communication, and executes a voice communication. When the voice communication ends, the wireless communication terminal performs a connection releasing process on the wireless communication system for voice communication, performs a temporal withdrawal cancelling (Resume) process on the LTE system, and returns to a mode of standing by for the LTE system. The operation of the CS Fallback is not limited to the audio incoming-call receiving process, and is the same operation in the case of an audio outgoing-call (origination-call) transmitting process.
As explained above, the wireless communication terminals which adopt an LTE that can normally stand by only for the LTE system can reduce a current consumption in comparison with the wireless communication terminals which adopt an LTE that can stand by for both wireless communication system for voice communication and LTE system. In addition, the wireless communication terminals which adopt the LTE that can stand by only for the LTE system also has an advantage of receiving an incoming call (see, for example, Non-patent Literature: 3GPP TS 23.272 V8.4.0 (2009-06), “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Circuit Switched Fallback in Evolved Packet System; Stage 2 (Release 8)”).
However, according to the conventional wireless communication terminals employing the LTE, when an audio incoming call or an audio outgoing call is made successively in a short period, e.g., when a user makes redialing immediately after a communication started by an audio incoming call ends or when the user immediately makes a call to a communication counterparty because another communication counterparty did not respond although an audio call transmitting process has been performed, the temporal withdrawal process of the LTE system and the temporal withdrawal cancelling process thereof are both activated, bringing about a problem that a transmitting process takes time. Moreover, according to the conventional wireless communication terminals employing the LTE, a control message for the temporal withdrawal cancelling process and a control message for the temporal withdrawal process are exchanged over radio in a short period, bringing about a problem that radio resources are wasted.
Furthermore, the similar problems to the foregoing problems generally happen in wireless communication terminals each having a first wireless communication unit which performs data communication on a first wireless communication scheme and a second wireless communication unit which communicates in a second wireless communication scheme enabling a voice communication.